Sony TC-800 portable reel-to-reel - UK Vintage Radio Repair and Restoration Discussion Forum

TonyDuell · 29th Apr 2016, 6:52 pm

One of the items that I bought at the museum tabletop sale last Sunday was a Sony TC-800. This is a battery/mains portable reel-to-reel tape recorder.

I have downloaded a TC-800 service manual (I think it's OK to say that, the manual does not seem to be available from 'the top right'). The same manual is available from Elektrotanya, Hifi Engine and Hifi Manuals.

This manual is for a 3 speed machine. Mine is a 2 speed machine (and the user manual that came with it also describes a 2 speed unit). Looking inside the machine the audio PCB and deck mechanics agree with the service manual, the 'servo' (motor speed control) board is totally different. This machine (both the one I have and the one in the service manual) has an electronically-controlled DC motor, the speed control is entirely electronic, there is no idler that gets shifted or anything like that.

When I say 'totally different' the (3 speed) board in the service manual has a transformer in the control path, the (2 speed) board in the machine had no transformer on it.

Was the design modified at some point? If so, why? Does anyone have a circuit diagram for the 2 speed version (to save me a day or so tracing it out

)

The user manual mentions an RM-5 (wired) remote control) that connects to the REMote and SPEED CONTROL sockets on the side. This allowed the user to stop the tape and also to slow it down. I assume the former was just a switch wired to the REMote socket. The speed control looks to be nothing more than a variable resistor. Does anyone know if that guess is correct and if so, what value it was?

Finally, the unit can run off 8 D-size cells fitted internally, but there is also a 4 pin power connector on the side. 2 pins for a 12V DC input and 2 pins for mains (looking at the way the mains transformer is wired, I am pretty sure it's 240V mains). There is also a swtch contact opened by (presumably) a ridge on the cable connector that disconnects the internal batteries when you connect said cable. I have not been able to find a source of the mains or DC cables (the user manual mentions one for 12V cars and one, presumably with some kind of electronic inverter in it, for 6V cars). Has anyone found a way of making said connector?

-tony

JohnBHanson · 2nd May 2016, 10:07 am

I have the diagram for the servo for the TC800-B which is a four speed machine - see pdf. This is a non-transformer version of the servo control. Also of use is the TC800-B has the speed control build in (R103+R104). I believe that if you build this little circuit as a plug in unit it should work with the TC800.

TonyDuell · 2nd May 2016, 3:46 pm

Thank you for that. It should be a good start when I start seriously looking at the board in mine.

I am pretty sure the external speed controller for mine is just a variable resistor, maybe with other fixed resistors in series or parallel. The manual I have for the 3 speed TC800 shows a 33R and 680R in parallel if nothing is plugged in, when you plug in the speed controller the 33R is disconnected and the controller is in parallel with the 680R. I suspect the simplest thing for me to do is to experiment with a few resistors connected to a plug (inserting the plug disconnects the 33R)

TonyDuell · 5th May 2016, 8:20 pm

A short update on this machine...

I have removed the 'servo' board and am attempting to trace out as much of the schematic as I need to (guided by the diagram above and the 3-speed version service manual). Interestingly, the 'Speed Control' socket on this machine simply shorts the 2 wires together when nothing is plugged in, so I guess a variable resistor connected there and set to 0 ohms will give the marked speed, higher resistances will slow it down.

I need to totally strip and clean the mechanical side. Lots of solid grease.

I have bought the 12V car battery cable (DCC-2AW) on Ebay. Paid more than I did for the machine, but said cable is brand new in box. It's also surprisingly complicated. The tape recorder runs off 12V, so I had expected the 12V car cable to be just a cable, maybe with a reverse protection diode or something. In fact there's a 3 (germanium) transistor low-drop-out regulator circuit in there. In a nice, screwed-together metal box (it even has a magnet to stick to the car body).

29th Apr 2016, 6:52 pm	#1
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,225	Sony TC-800 portable reel-to-reel One of the items that I bought at the museum tabletop sale last Sunday was a Sony TC-800. This is a battery/mains portable reel-to-reel tape recorder. I have downloaded a TC-800 service manual (I think it's OK to say that, the manual does not seem to be available from 'the top right'). The same manual is available from Elektrotanya, Hifi Engine and Hifi Manuals. This manual is for a 3 speed machine. Mine is a 2 speed machine (and the user manual that came with it also describes a 2 speed unit). Looking inside the machine the audio PCB and deck mechanics agree with the service manual, the 'servo' (motor speed control) board is totally different. This machine (both the one I have and the one in the service manual) has an electronically-controlled DC motor, the speed control is entirely electronic, there is no idler that gets shifted or anything like that. When I say 'totally different' the (3 speed) board in the service manual has a transformer in the control path, the (2 speed) board in the machine had no transformer on it. Was the design modified at some point? If so, why? Does anyone have a circuit diagram for the 2 speed version (to save me a day or so tracing it out ) The user manual mentions an RM-5 (wired) remote control) that connects to the REMote and SPEED CONTROL sockets on the side. This allowed the user to stop the tape and also to slow it down. I assume the former was just a switch wired to the REMote socket. The speed control looks to be nothing more than a variable resistor. Does anyone know if that guess is correct and if so, what value it was? Finally, the unit can run off 8 D-size cells fitted internally, but there is also a 4 pin power connector on the side. 2 pins for a 12V DC input and 2 pins for mains (looking at the way the mains transformer is wired, I am pretty sure it's 240V mains). There is also a swtch contact opened by (presumably) a ridge on the cable connector that disconnects the internal batteries when you connect said cable. I have not been able to find a source of the mains or DC cables (the user manual mentions one for 12V cars and one, presumably with some kind of electronic inverter in it, for 6V cars). Has anyone found a way of making said connector? -tony

2nd May 2016, 3:46 pm	#3
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,225	Re: Sony TC-800 portable reel-to-reel Thank you for that. It should be a good start when I start seriously looking at the board in mine. I am pretty sure the external speed controller for mine is just a variable resistor, maybe with other fixed resistors in series or parallel. The manual I have for the 3 speed TC800 shows a 33R and 680R in parallel if nothing is plugged in, when you plug in the speed controller the 33R is disconnected and the controller is in parallel with the 680R. I suspect the simplest thing for me to do is to experiment with a few resistors connected to a plug (inserting the plug disconnects the 33R)

5th May 2016, 8:20 pm	#4
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,225	Re: Sony TC-800 portable reel-to-reel A short update on this machine... I have removed the 'servo' board and am attempting to trace out as much of the schematic as I need to (guided by the diagram above and the 3-speed version service manual). Interestingly, the 'Speed Control' socket on this machine simply shorts the 2 wires together when nothing is plugged in, so I guess a variable resistor connected there and set to 0 ohms will give the marked speed, higher resistances will slow it down. I need to totally strip and clean the mechanical side. Lots of solid grease. I have bought the 12V car battery cable (DCC-2AW) on Ebay. Paid more than I did for the machine, but said cable is brand new in box. It's also surprisingly complicated. The tape recorder runs off 12V, so I had expected the 12V car cable to be just a cable, maybe with a reverse protection diode or something. In fact there's a 3 (germanium) transistor low-drop-out regulator circuit in there. In a nice, screwed-together metal box (it even has a magnet to stick to the car body).